Conventional industrial high speed cylinder sewing machines generally can be divided into longitudinal-cylinder sewing machine and transverse-cylinder sewing machine. The longitudinal-cylinder sewing machine has a cylinder axis directed towards the operator; the axial direction of the transmission axle of the entire sewing machine is also the same. By contrast, the cylindrical axis of the transverse-cylinder sewing machine is transverse at the front side of the operator. The longitudinal-cylinder sewing machine is widely used for sewing cuffs, elastic wristbands, auxiliary sewing or ornamental sewing for circular articles and the like. In terms of operational convenience, the adjustment mechanisms of longitudinal-cylinder sewing machines are hindered by their sewing mechanisms at the front end of the cylinder; they are both inconvenient for operation and adjustment.
In addition, during operation, the internal mechanisms of the sewing machine need lubrication to smooth the operation of movable parts. Lubrication is usually accomplished by forming a hollow interior in the transmission shaft or some larger size component and stuffing with oil-dipped cotton strands or floss. During operation, the lubricating oil seeps through the cotton strands/floss to grease the movable parts and thus ensure smooth operation. Such a design is applicable only to larger components of a sewing machine. It is not suitable for smaller elements.
Most important, the conventional differential fabric driving teeth structure is driven by a coarse and fine stitch adjustment structure, and is operated in a passive mode. There is a suspended arm bridging the stitch adjustment structure and the differential fabric driving teeth structure to link the operation so that the driven stitch adjustment structure also drives the differential fabric driving teeth structure during operation. Such a design has to increase the swing amplitude of the differential fabric driving teeth structure linked by the stitch adjustment structure when there is a need to alter the differential ratio of the differential fabric driving teeth structure. In fact, with the linkage bar lengthened, it becomes a heavy transmission element of the stitch adjustment structure and will generate vibration and noise. Furthermore, demand for fabric extension and retraction is higher these days, the differential ratio of the differential fabric driving teeth structure also has to increase to meet this requirement. Hence the passive driven operation of the differential fabric driving teeth structure is not desirable. A design to generate independent eccentric swing is needed.